This invention relates to a mechanical re-pointing and grouting device.
Manual re-pointing is a skilled, labor intensive, and slow task that needs a high level of skill to achieve fully filled joints with a satisfactory appearance. When manually re-pointing in the traditional manner, joints are filled from the front by mechanical pressure on the re-pointing material by the brick layer's pointing trowel. To fill to any depth needs a soft re-pointing material because if it is stiff, it cannot be manually pushed into the narrow joint by the pointing trowel. The required soft wet re-pointing material tends to bleed onto the face of the brick, producing an unsatisfactory appearance. Mechanical re-pointing can be much faster, can achieve fully filled joints because they are filled from the back of the joint rather than from the front and, hence, can be much more cost effective. However, the equipment that is currently available has a number of disadvantages.
Grouting is the process of forcing a fluid grouting material into a narrow gap or joint between two surfaces with the intention of completely filling the gap so that when the grouting material has solidified, it will increase the load bearing capacity between the two surfaces and seal the gap or joint. Applications of grouting include the injection of grout material between structural steel work and its supporting concrete base, the injection of grout material between stone work in such applications as harbor walls, embankments etc., the injection of grout material between flagstones, the injection of grout material to support heavy machines and structures, and many more similar applications. Current practice involves either manual methods, which are slow and give results of indeterminate quality, or the application of grout pumping machinery, which is expensive.
There are a number of patented mechanical re-pointing and grouting devices currently available that utilize electrical, hydraulic, or pneumatic power to propel the grouting mix into the joint to be grouted. These devices fall into three types: screw auger; piston; and pressure vessel.
The screw auger device transports the re-pointing or grouting material through a nozzle to the joint being re-pointed or grouted. An electric, pneumatic, or hydraulic motor drives the auger. Screw auger devices are heavy because of the electrical, hydraulic, or pneumatic drive, and they can cause separation of the mix because of the vibration of the rotating auger. Specific grain size material and special plasticizers have to be used to facilitate the flow of the re-pointing or grouting material. Because of the abrasive nature of the re-pointing or grouting material, screw auger devices are subject to wear of the auger, auger housing, and auger bearings. A typical device of this type is described in U.S. Pat. No. 5,054,658.
Piston type devices apply pressure to the re-pointing or grouting material via a piston in a cylinder and force it through a nozzle into the joint. Electrical, pneumatic, hydraulic, or manual drives are used to produce the linear motion of the piston required to force the re-pointing or grouting material into the joint. Piston type devices require a high pressure to operate because of the resistance to flow of the re-pointing or grouting material and friction between the piston and cylinder. They also are subject to piston and cylinder wear because of the abrasive nature of the re-pointing or grouting material, although this can be reduced by incorporating the mixture in a foil bag which is inserted in the cylinder (see, for example, U.S. Pat. No. 5,449,096). A typical piston type device is described in patent German Patent Publication No. 296 05 341.
Pressure vessel type devices (such as shown in British Patent Application No. 2,011,518, and British Patent Application No. 2,267,735) are normally a conical shaped pressure vessel with the apex pointing down and containing the re-pointing or grouting material. A flexible hose or pipe, having a discharge valve and nozzle fitted at one end, is connected at the other end to the cone of the pressure vessel at its lowest point. The pressure vessel is sealed, and compressed air is admitted to the vessel in the space above the re-pointing or grouting material so that it is forced to pass from the vessel through the flexible hose or pipe past the discharge valve and through the nozzle to the joint to be grouted. Some designs (such as shown in British Patent Application No. 2,011,518) admit air to the nozzle to aid the flow of re-pointing or grouting material through the valve.
Due to the high frictional resistance of the re-pointing or grouting material as it passes through the vessel along the discharge pipe and through the discharge valve, the air pressure in the pressure vessel has to be high, requiring it to be strong and, as a result, heavy. Such an air vessel is not easily transported. To overcome difficulties in moving the pressure vessel, some devices use long hoses to enable coverage of a larger area of re-pointing. However, the longer the hose, the greater the friction loss, and the greater the air pressure required in the pressure vessel. The hose or pipe must be of sufficiently large diameter to allow flow of the re-pointing or grouting material, but not too large and heavy with the dense re-pointing or grouting material, to restrict the maneuverability of the nozzle. Also, if the joint to be filled is above the pressure vessel, the air pressure must be increased to overcome this static head. The discharge valve must be designed so that it does not restrict the flow when open, but closes effectively to stop the flow when required. The abrasive nature of the re-pointing or grouting material requires the discharge valve be manufactured from abrasion resistant materials. The hose and discharge valve combination is difficult to clean, and if the mix should solidify and cure before it is removed, then its subsequent removal is likely to lead to damage.
All the devices discussed above have operating, cost, and design problems.